I wonder if you are particularly closer to say, one of them, in which you could maybe go out for a coffee or a catch-up and tell them how you feel, and say you are having thoughts on how you can approach this/address the issue.
For me, I'd have to. So during school for me, I got along with everyone and had a few close friends, there was a group of girls 'the girls' who were tight knit, I always wished I could be a part of it, however I was best friends with one of the girls, but never really included in the group. But because I had other friends it didn't bother me.
Fast forward to being in my 20's, with some lovely friends and my two toddler boys, watching this 'girl group' over the years, argue, bitch, get along again, and fall out, I really look back and think, you know what, I'm glad I wasn't part of that? ...
I've got close friends and a peaceful life.
All I'm really saying is that for me personally, I'd have to address it, if they've got a problem with you for nothing, if they're deciding to be distant towards you, if you can't share your life and kids and pregnancies with these girls, are they even friends you want in your life ?
Going back to what I'd said at first however, I'd go out with one of them alone and explain that this really deep down is upsetting you and getting to you, and if it's something they've noticed too.